The present invention relates generally to packaging materials and, more specifically, to a machine and method for producing packaging cushioning from sheets of a selected substrate, such as paper.
Machines for producing packaging cushioning from paper are well-known in the art. Such machines generally operate by pulling a web of paper from a roll, manipulating the paper web in such a way as to convert the paper into packaging cushioning, and then severing the cushioning into cut sections of a desired length.
While such machines are widely used and have been commercially successful, in many applications, there is a need for improved functionality. For example, paper rolls tend to be quite heavy and cumbersome to lift and load onto cushion conversion machines. Although the volume of cushioning that can be produced from a roll of paper tends to off-set the weight disadvantage for high-volume packaging operations, for lower-volume packaging operations, a lighter, easier-to-handle alternative would be preferred.
Moreover, while severing mechanisms in roll-fed machines provide a workable means for producing cushions of a desired length, such mechanisms present ongoing safety concerns, in both the design and operation of such machines.
As a result, Sealed Air Corporation (US), assignee of the present invention, has developed a machine that produces packaging cushions of a desired length without the need for a severing or perforation mechanism, by joining individual sheets of paper together in such a way that packaging cushions having any desired length can be produced. Such machine, which is described in U.S. patent application Ser. No. 12/583,749, also allows the density of the resultant packaging cushions to be varied as desired to suit the weight or nature of the objects being packaged. This is accomplished by overlapping the sheets to a desired extent, in order to achieve a desired density in the resultant packaging cushions.
One area for improvement that has been identified with the '749 machine concerns the tracking and handling of the paper sheets, particularly when making higher-density packaging cushions. In general, the density of the packaging cushions is proportional to the degree of overlap between successive sheets. Thus, the greater the degree of overlap between adjacent sheets, the higher will be the density of the resultant cushion. It has been found, however, that above a certain point of overlap, the increased resistance to forward movement of the paper sheets results in poor tracking, rippling, and then jamming of the sheets, resulting in the necessity of shutting down the machine to clear the jams, which causes paper to be wasted and production time to be lost.
Accordingly, there is a need in the art for an improvement to sheet-fed packaging-cushion machines, which will reduce or prevent paper jams while still allowing higher-density packaging cushions to be produced.